Optical processing device employing a digital micromirror device (DMD) and having reduced wavelength dependent loss

Abstract

An optical arrangement includes an actuatable optical element and a compensating optical element. The actuatable optical element is provided to receive an optical beam having a plurality of spatially separated wavelength components and diffract the plurality of wavelength components in a wavelength dependent manner. The compensating optical element directs the optical beam to the actuatable optical element. The compensating optical element compensates for the wavelength dependent manner in which the wavelength components are diffracted by the actuatable optical element.

The invention claimed is: 
     
       1. An optical arrangement comprising:
 an actuatable optical element for receiving an optical beam having a plurality of spatially separated wavelength components and diffracting the plurality of wavelength components in an inherently wavelength dependent manner; and 
 a compensating optical element directing the optical beam to the actuatable optical element, said compensating optical element compensating for the inherent wavelength dependent manner in which the wavelength components are diffracted by the actuatable optical element. 
 
     
     
       2. The optical arrangement of  claim 1  further comprising at least two optical input/output ports for receiving the optical beam, wherein the actuatable optical element selectively directs at least one of the diffracted wavelength components to one of the optical input/output ports, said compensating optical element reducing optical coupling loss in the diffracted wavelength component caused by the wavelength dependent manner in which the wavelength components are diffracted by the actuatable optical element. 
     
     
       3. The optical arrangement of  claim 1  further comprising a collimating optical element for collimating the plurality of wavelength components, said actuatable optical element including a digital micromirror device (DMD) having an array of individual actuatable mirror elements for selectively reflecting the wavelength components, said array of mirrors being oriented such that without provision of the compensating optical element an optical path length between the collimating optical element and the DMD differs from wavelength component to wavelength component, said compensating optical element adjusting the optical path lengths so that they are equal in length for each wavelength component. 
     
     
       4. The optical arrangement of  claim 1  wherein said compensating optical element includes at least one surface configured to compensate for the wavelength dependent manner in which the wavelength components are diffracted by the actuatable optical element. 
     
     
       5. The optical arrangement of  claim 4  wherein the surface is cylindrical in shape. 
     
     
       6. The optical arrangement of  claim 4  wherein the surface has a shape that conforms to a 5 th  term in a Zernike polynomial. 
     
     
       7. The optical arrangement of  claim 4  further comprising a collimating optical element for collimating the plurality of wavelength components, wherein the compensating optical element includes at least one refractive and/or reflective surface and is further configured to adjust an optical path length experienced by the wavelength components between the collimating optical element and the actuatable optical element so that the wavelength components are focused onto the actuatable optical element. 
     
     
       8. The optical arrangement of  claim 7  wherein the compensating optical element includes a prism. 
     
     
       9. The optical arrangement of  claim 2  wherein the at least two input/output ports comprises an optical launch arrangement configured to receive at least one input optical beam and output a spatially overlapping, angularly multiplexed optical beam that is focused at a virtual focal point. 
     
     
       10. The optical arrangement of  claim 9  wherein the optical launch arrangement includes a fiber assembly for securing an array of optical fibers and an asymmetric lenslet array having a first surface with a pair of collimating lens in registration with each optical fiber in the array and a second surface with a coupling lens in registration with each pair of collimating lenses. 
     
     
       11. An optical processing device comprising:
 at least two optical input/output ports for receiving an optical beam; 
 a dispersion element receiving the optical beam from one of the ports and spatially separating the optical beam into a plurality of wavelength components; 
 a collimating lens for collimating the plurality of wavelength components; and 
 an actuatable optical element for receiving the collimated wavelength components from the collimating element and diffracting the plurality of wavelength components in an inherently wavelength dependent manner; and 
 a compensating optical element located in an optical path between the dispersion element and the actuatable optical element, said compensating optical element compensating for the inherent wavelength dependent manner in which the wavelength components are diffracted by the actuatable optical element. 
 
     
     
       12. The optical processing device of  claim 11  wherein the actuatable optical element selectively directs at least one of the diffracted wavelength components to one of the optical input/output ports, said compensating optical element reducing optical coupling loss in the diffracted wavelength component caused by the wavelength dependent manner in which the wavelength components are diffracted by the actuatable optical element. 
     
     
       13. The optical processing device of  claim 11  wherein said actuatable optical element includes a digital micromirror device (DMD) having an array of individual actuatable mirror elements for selectively reflecting the wavelength components, said array of mirrors being oriented such that without provision of the compensating optical element an optical path length between the collimating lens and the DMD differs from wavelength component to wavelength component, said compensating optical element adjusting the optical path lengths so that they are equal in length for each wavelength component. 
     
     
       14. The optical processing device of  claim 11  wherein said compensating optical element includes at least one surface configured to compensate for the wavelength dependent manner in which the wavelength components are diffracted by the actuatable optical element. 
     
     
       15. The optical processing device of  claim 14  wherein the surface is cylindrical in shape. 
     
     
       16. The optical processing device of  claim 14  wherein the surface has a shape that conforms to a 5 th  term in a Zernike polynomial. 
     
     
       17. The optical processing device of  claim 14  wherein the compensating optical element includes at least one refractive and/or reflective surface and is further configured to adjust an optical path length experienced by the wavelength components between the collimating lens and the actuatable optical element so that the wavelength components are focused onto the actuatable optical element. 
     
     
       18. The optical processing device of  claim 17  wherein the compensating optical element includes a prism. 
     
     
       19. The optical processing device of  claim 11  wherein the at least two input/output ports comprises an optical launch arrangement configured to receive at least one input optical beam and output a spatially overlapping, angularly multiplexed optical beam that is focused at a virtual focal point. 
     
     
       20. The optical processing device of  claim 19  wherein the optical launch arrangement includes a fiber assembly for securing an array of optical fibers and an asymmetric lenslet array having a first surface with a pair of collimating lens in registration with each optical fiber in the array and a second surface with a coupling lens in registration with each pair of collimating lenses. 
     
     
       21. A method of processing an optical signal, comprising:
 diffracting a plurality of spatially separated wavelength components in an inherently wavelength dependent manner with an actuatable optical element; and 
 compensating for the inherent wavelength dependent manner in which the wavelength components are diffracted by the actuatable optical element. 
 
     
     
       22. The method of  claim 21  further comprising:
 collimating the plurality of wavelength components; and 
 adjusting an optical path length experienced by the collimated wavelength components before being diffracted so that the collimated wavelength components all traverse a common optical path length. 
 
     
     
       23. The method of  claim 22  wherein compensation for the wavelength dependent manner in which the wavelength components are diffracted by the actuatable optical element and adjustment of the optical path length are performed by a common optical element.